Combinatorial weighing apparatus

ABSTRACT

Disclosed in a combinatorial weighing apparatus having a plurality of weighing hoppers, a plurality of weighing machines, associated with respective ones of the weighing hoppers, for weighing or counting articles introduced into each of the weighing hoppers, and a chute for collecting the articles discharged from the weighing hoppers. The apparatus operates by computing combinations based on weight values provided by the weighing machines, and causing weighing hoppers, belonging to a combination selected as a result of the combinatorial computations, to discharge their articles into the chute one hopper at a time with a predetermined time delay intervening between the discharge operations.

This is a continuation of co-pending application Ser. No. 414,678 filedon Sept. 3, 1982.

BACKGROUND OF THE INVENTION

This invention relates to a combinatorial weighing apparatus and, moreparticularly, to a combinatorial weighting apparatus of the type thatoperates by finding the weights of articles charged into a plurality ofweighing hoppers, and discharging from proper ones of the weighinghoppers those articles which, in combination (referred to as the "best"combination"), give a total weight equal to a set target weight orclosest to the set target weight within preset allowable limits.

It is general practice to employ a computerized combinatorial weighingapparatus, referred to as a computer scale, when weighing out a categoryof articles having widely different unit weights from one to another.Examples of such articles are vegitables and fruits, confectioneries,perishables and fabricated parts. As shown in FIG. 1, a combinatorialweighing apparatus of the aforementioned type operates by measuring theweights of articles charged into a plurality of weighing hoppers 2-1,2-2, . . . 2-n, the measurements being performed by weighing machines3-1, 3-2, . . . 3-n provided on the respective weighing hoppers,selecting the combination of articles that gives a total weight closestto a preset target weight within preset allowable limits, the selectionbeing based upon the weights measured by the weighing machines,discharging the selected articles from the weighing hoppers containingthem, collecting the discharged articles in a collecting chute 4 anddelivering them to a timing hopper 5, subsequently replenishing theemptied weighing hoppers with new articles to be weighed, finding thenext combination of articles to be discharged, and then repeating theforegoing cycle to continue the weighing out of articles in automaticfashion.

FIG. 2 illustrates the general construction of the combinatorialweighing apparatus described above. Numeral 1 denotes a dispersing tableof vibratory conveyance type. Articles to be weighed are introduced ontothe dispersing table 1 and imparted with vibratory motion for apredetermined length of time so as to be dispersed radially outwardlyfrom the center of the table. Numerals 2-1, . . . 2-n denote n-number ofweighing stations which are arranged around the dispersing table 1 alongradially extending lines to receive the articles dispersed by the table.Each weighing station includes a dispersing feeder 2a, a pool hopper 2b,a pool hopper gate 2c, a weighing hopper 2d, a weight sensor (weighingmachine) 3, a weighing hopper gate 2f, and a hopper drive unit 2g. Thedispersing feeder 2a is an independently vibratable conveyance devicefor feeding the articles by means of vibration, and includes anelectromagnet 2a-1 and a trough 2a-2 which is vibrated by the magnet2a-1. Each dispersing feeder 2a is so arranged that the articlesreceived from the centrally located dispersing table 1 can be introducedinto the corresponding pool hopper 2b disposed therebelow. The poolhopper gate 2c is provided on each pool hopper 2b in such a manner thatthe articles received in the pool hopper 2b are released into theweighing hopper 2d when the pool hopper gate 2c is opened under thecontrol of the corresponding hopper drive unit 2g. Each weight sensor 3,accompanying a respective one of the weighing hoppers 2d, is operable tomeasure the weight of the articles introduced into the correspondingweighing hopper, and to apply an electrical signal indicative of themeasured weight to a combination control unit, shown in FIG. 2. Thecombination control unit then selects the combination of articles (knownas the "best" combination) that gives a total weight equal to a targetvalue or closest to the target value within preset allowable limits, aswill be described below in further detail. Each weighing hopper 2d isprovided with its own weighing hopper gate 2f. Only the weighing hoppergates 2f of those weighing hoppers that give the best combination areopened under the control of the hopper drive units 2g, these gates 2fdischarging the articles into a common chute 4 where they are collectedtogether. The collecting chute 4 has the shape of a funnel and is soarranged as to receive the articles from any of the circularly arrayedweighing hoppers 2d via the hopper gates 2f, which are located above thefunnel substantially along its outer rim. The articles received by thecollecting chute 4 are collected at the centrally located lower endthereof by falling under their own weight or by being forcibly shiftedalong the inclined wall of the funnel by a mechanical scraper or thelike, which is not shown.

In operation, articles are charged into each of the pool hoppers 2b andweighing hoppers 2d. The weighing sensors 3 associated with the weighinghoppers 2d measure the weights of the articles and supply thecombination control unit, not shown, with signals indicative of themeasured weight values, denoted L₁ through L_(n). The combinationcontrol unit computes combinations based on the weight values L₁ throughL_(n) and selects the best combination of articles that gives a totalweight closest to a target weight within preset allowable limits. Thehopper drive units 2g respond by opening the prescribed weighing hoppergates 2f based on the best combination, whereby the articles giving saidbest combination are released into the collecting chute 4 from thecorresponding weighing hoppers 2d to be fed into the timing hopper 5.This will leave the selected weighing hoppers 2d empty. Subsequently,therefore, the pool hopper gates 2c corresponding to the empty weighinghoppers 2d are opened to introduce a fresh supply of the articles fromthe respective pool hoppers 2b into said weighing hoppers 2d, leavingthese pool hoppers 2b empty. Accordingly, the dispersing feeders 2awhich correspond to the empty pool hoppers 2b are vibrated for apredetermined period of time to deliver a fresh supply of the articlesto these pool hoppers. This restores the weighing apparatus to theinitial state to permit resumption of the control operation forselecting the best weight combinations in the manner described. Thus,weighing by the combinatorial weighing apparatus may proceed incontinuous fashion by repeating the foregoing steps.

FIGS. 3 and 4 illustrate another example of a combinatorial weighingapparatus of the above type, improved to raise the discharge rate of thearticles. Here the apparatus is provided with inner and outer chutes 4a,4b having upper open ends 4c, 4d which are concentrically arranged, andlower open ends 4e, 4f arranged side by side, with the inner chute 4apenetrating through the conical wall of the outer chute 4b at the middleportion thereof. Each of the weighing hoppers 2-1, 2-2, . . . 2-n isprovided with a pair of independently openable weighing hopper gates2f₁, 2f₂. According to this arrangement, opening predetermined ones ofthe weighing hopper gates makes it possible to discharge articlesselectively into the inner and outer chutes 4a, 4b from the weighinghoppers. With a combinatorial weighing apparatus of this kind, theweights of the articles fed into the weighing hoppers 2-1, 2-2, . . .2-n are weighed by the respective weight sensors 3-1, 3-2, . . . 3-n,and signals indicative of the weighed values are sent to a combinationcontrol unit, which is not shown, for computing combinations based uponthese weight values. More specifically, the combination control unit isadapted to either (a) simultaneously select two "best" combinationsgiving first best and second best values equal to a target weight orclosest to the target weight within preset allowable limits, or (b)select one "best" combination, as defined above, and then recomputecombinations based on the remaining weight values and select anothersingle "best" combination based on this second round of computations.When two sets of combinations have been selected through either of theabove methods, the weighing hopper gates 2f₁, 2f₁ . . . of the weighinghoppers corresponding to the first selected combination are opened todischarge their articles into, say, the inner chute 4a, and the weighinghopper gates 2f₂ , 2f₂ . . . of the weighing hoppers corresponding tothe second selected combination are opened to discharged their articlesinto the outer chute 4b. Both sets of the discharged articles arecollected by the respective inner and outer chutes 4a, 4b and deliveredto timing hoppers 5, 5'.

Various configurations of the above-described combinatorial weighingapparatuses exist, but in all of them one or a plurality of combinationsare selected in each single weighing cycle, and the articles aredischarged from the selected weighing hoppers at one time. In otherwords, with the conventional combinatorial weighing arrangements, adischarge command signal is transmitted to all of the selected weighinghoppers simultaneously, causing these hoppers to release their articlesinto the chute 4 (FIG. 1), or into the inner and outer chutes 4a, 4b(FIG. 3), at the same time. As the articles discharged en masse in thisfashion converge at the bottom opening of the chute, therefore, theopening is likely to be blocked as articles of a poor flowabilityexhibit a bridging phenomenon and pile up faster than they can bedelivered from the opening. This makes it impossible to deliver thearticles to the awaiting timing hopper. An additional defect isexhibited by the combinatorial weighing apparatus of FIG. 3 having twoarticle discharge paths, wherein the discharged articles, irrespectiveof their flowability, form bridges and pile up also at the portion ofthe outer chute 4b, where it is narrowed by the intersecting inner chute4a, when a large quantity of the articles are released into the outerchute 4b at one time. This prevents the delivery of the articles fromthe outer chute.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide acombinatorial weighing apparatus in which discharged articles will notform bridges and pile up at the lower opening of a collecting chute.

Another object of the present invention is to provide a combinatorialweighing apparatus in which discharged articles can be delivered from acollecting chute in reliable fashion regardless of the type of articleor the shape of the chute.

A further object of the present invention is to provide a combinatorialweighing apparatus in which an article discharge command signal issuccessively delivered, after a suitable time delay, to each weighinghopper selected by a combinatorial computation cycle, whereby saidweighing hoppers may be opened in successive fashion to discharge theirarticles into a collecting chute in turn.

Other features and advantages of the invention will be apparent from thefollowing description taken in conjunction with the accompanyingdrawings in which like reference characters designate the same orsimilar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 3 are schematic views illustrating examples of acombinatorial weighing apparatus according to the prior art;

FIG. 2 is a view showing the detailed construction of the combinatorialweighing apparatus depicted in FIG. 1;

FIG. 4 is a perspective view of the collecting chutes shown in FIG. 3;

FIGS. 5 and 6 are schematic views illustrating an embodiment of thepresent invention;

FIG. 7 is a block diagram of a combination computing unit shown in FIGS.5 and 6;

FIG. 8 is a block diagram illustrating a discharge control unit; and

FIG. 9 is a schmatic view of another embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 5 and 6, a combinatorial weighing apparatus inaccordance with the present invention includes weighing hoppers 2-1,2-2, . . . 2-n for receiving suitable quantities of articles to beweighed, weight sensors 3-1, 3-2, . . . 3-n for weighing the articlesreceived in respective ones of the weighing hoppers 2-1, 2-2, . . . 2-n,and a chute 4, in the shape of an inverted frusto-cone, for collectingthe articles discharged from the weighing hoppers. The weighing hoppers2-1, 2-2, . . . 2-n and associated weight sensors 3-1, 3-2, . . . 3-nare arrayed above the outer rim of the cone 4 and equally spaced fromone another, as will be understood from FIG. 5. Each weighing hopper2-1, 2-2, . . . 2-n has an openable weighing hopper gate 2f provided atthe lower portion thereof, with predetermined ones of the weighinghopper gates 2f being opened in response to a discharge command signalto release the corresponding articles into the chute 4. Also providedare a combination computing unit 6, to which the weight sensors 3-1,3-2, . . . 3-n are connected to supply the unit with signals indicativeof the measured weight values, and a discharge control unit 7 connectedbetween the combination computing unit 6 and each of the weighinghoppers 2-1, 2-2, . . . 2-n to successively provide the weighinghoppers, belonging to a combination selected on the basis ofcomputations performed by the computing unit 6, with a discharge commandsignal delivered to one after another of the hoppers with apredetermined time delay intervening between each delivery of thesignal. In this example the discharge control unit 7 sends the dischargecommand signal to the selected hoppers in increasing numerical order.

In operation, the weight sensors 3-1, 3-2, . . . 3-n weigh the articlesintroduced into the respective weighing hoppers 2-1, 2-2, . . . 2-n, anddeliver signals indicative of these weights to the combination computingunit 6. The latter responds by computing combinations based on theweight values, and by selecting one combination that gives a totalweight value equal to a preset target weight or closest to the targetweight within preset allowable limits. For example, assume that thecombination computing unit 6 selects the five weight sensors 3-1, 3-3,3-5, 3-8, 3-n as making up the best combination. The combinationcomputing unit 6, immediately upon selecting this combination, providesthe discharge control unit 7 with a discharge command signal for each ofthe weighing hoppers 2-1, 2-3, 2-5, 2-8, 2-n that correspond to theselected weight sensors 3-1, 3-3, 3-5, 3-8, 3-n. In turn, the dischargecontrol unit 7 sends the acquired discharge command signals, aftersuccessive predetermined time delays, to the weighing hoppers inincreasing numerical order, that is, to weighing hoppers 2-1, 2-3, 2-5,2-8, 2-n in the order mentioned. The weighing hoppers, upon receipt ofthe discharge command signal, successively release their articles intothe chute 4 as their respective weighing hopper gates 2f are opened inthe above-mentioned order in response to the discharge signal. When thelast weighing hopper 2-n releases it articles so that all of theselected weighing hoppers 2-1, 2-3, 2-5, 2-8, 2-n are empty, thesehoppers are supplied afresh with articles by means of corresponding poolhoppers, not shown. The weight sensors 3-1, 3-3, 3-5, 3-8, 3-ncorresponding to the resupplied weighing hoppers weigh the newlysupplied articles and send signals indicative of the measured weights tothe combination computing unit 6. The latter again computes combinationsbased on the weight values just transmitted and on the already knownweight values which were not selected by the previous combinatorialcomputation operation, and selects the best combination based on thislatest round of computations. These operations are repeated to dischargearticles from selected weighing hoppers into the chute 4 in continuousfashion.

In discharging the articles, the weighing hoppers selected as the resultof the combinatorial computations have their weighing hopper gates 2f,2f . . . opened one after another, with a suitable time delayintervening between each opening operation, in accordance with thedischarge command signals from the discharge control unit 7, so that thearticles are released into the chute 4 successively rather than enmasse. In other words, as a result of the foregoing operations, articlesfrom one weighing hopper at a time flow through the chute 4 so that thearticles do not form bridges and pile up at the constricted portion ofthe chute, enabling all kinds of articles to be delivered in reliablefashion. An additional advantage is that the chute 4 can be reduced insize since only small quantities of the articles flow down the chute atany given time.

It is obvious that the weighing hoppers 2-1, 2-2, . . . 2-n can be madeto discharge their articles in decreasing numerical order, and that thedischarge of articles can take place in random fashion when the weighinghoppers are circularly arrayed. What is essential is that the weighinghoppers release their articles in turn with a prescribed time delayintervening between each release.

Reference will now be had to the block diagram of FIG. 7 for a fullerdescription of the construction and operation of the combinationcomputing unit 6 shown in FIGS. 5 and 6. The combination computing unit6 includes registers 6a-1, 6a-2, . . . , 6a-n for storing weight valuesW1, W2, . . . Wn delivered by respective weight sensors 3-1, 3-2, . . .3-n, and an n-bit counter 6b for counting timing pulses TP of apredetermined frequency, and for generating combinations of the n-numberof weighing machines. These combinations will also be referred to as"combination patterns" where appropriate. Specifically, for n-number ofweighing hoppers, n combinations are possible when each combination iscomposed of one weighing hopper from the total of n weighing hoppers,n(n-1)/2! combinations are possible when each combination is composed oftwo weighing hoppers selected from said total, and, in general,n(n-1)(n-2) . . . (n-r+1)/r! combinations are possible when eachcombination is composed of r-number of weighing hoppers selected fromsaid total of n weighing hoppers. Accordingly, when the n-bit binarycounter 6b has counted 2^(n) -1 timing pulses TP, a total of 2^(n) -1different bit patterns, from 000 . . . 001 to 111 . . . 111, will havebeen generated. Therefore, if a correlation is established between thefirst bit and the first weight sensor 3-1, between the second bit andthe second weight sensor 3-2, and between third through n-th bits andthe third through n-th weight sensors 3-3 through 3-n, respectively,then the generated bit pattern will be an indication of theabovementioned combination pattern.

The generated bit pattern, indicative of the value of the count incounter 6b, is applied to a multiplexer 6c. The latter provides anarithmetic unit 6g with the weight values stored in those registers6a-1, 6a-2, . . . 6a-n, for the corresponding weight sensors, specifiedby the bit pattern. For instance, if the value of the count is1000101011 when n=10, then the arithmetic circuit 6g will receive theweight value outputs W1, W2, W3, W4, W6, W10 from the first, second,fourth, sixth and tenth weight sensors 3-1, 3-2, 3-4, 3-6 and 3-10,respectively. The arithmetic unit 6g also receives a signal W_(a),indicative of a target value, from a target weight register 6d whichstores the target weight. Numerals 6e and 6f denote upper and lowerlimit setting devices, respectively, for storing preset allowable limits(namely an upper limit or maximum value Ma, and a lower limit or minimumvalue Mi, respectively) for weight values. The minimum value Mi is setequal to the target value, as is customary. If it were set lower thanthe target value, the result could be delivery of articles having atotal weight less than that intended, and complaints might ensue.

The arithmetic unit 6g computes, and delivers a signal indicative of,the gross weight ΣW_(i) (=X) of the weight values received from themultiplexer, and also computes the difference between the gross weightΣW_(i) and the target value W_(a). The arithmetic unit 6g produces asignal A indicating the absolute value of the computed difference. Morespecifically, the arithmetic unit 6g performs the operations:

    ΣW.sub.i =X                                          (1)

    |ΣW.sub.i -W.sub.a |=A             (2)

and produces a signal representing the total weight ΣW_(i) (=X), as wellas a signal A representing the absolute value (hereafter referred tosimply as the "deviation") of the difference between the gross weightΣW_(i) and the set target weight W_(a). The value X is applied to acomparator 6h, whose output is connected to a counter 6i. The comparator6h discriminates whether the gross weight X lies in the range defined byM_(i) and M_(a). Specifically, if the following relation holds:

    M.sub.i ≦X≦M.sub.a                           (3)

then the comparator 6h will increment (count up) the counter 6i by one.A minimum deviation register 6j for storing the minimum deviation is setautomatically to the deviation A the first time only, and thereafter isupdated as the conditions warrant, as will be described later. In thecase where the minimum value M_(i) is set equal to the target weightvalue, it is permissible to initially set the minimum deviation register6j to the difference between the maximum value M_(a) and the targetvalue. A best combination memory 6k is adapted to store the bestcombination pattern. Numerals 6m and 6n denote gates. When the grossweight ΣW_(i) is within the preset allowable limits, a comparator 6pcompares the deviation value A, namely the output of the arithmetic unit6g, with the minimum deviation value, denoted by B, stored in theminimum deviation register 6j. When the inequality A<B holds, the outputof comparator 6p is such that the deviation value A is delivered forstorage to the minimum deviation register 6j through the gate 6m, andthe content (combination pattern) of counter 6b is delivered for storageto the best combination memory 6k.

Numeral 7 denotes the discharge control unit shown in FIGS. 5 and 6.When the content of counter 6i is one or more, the discharge controlunit 7, which receives a signal from memory 6k indicative of the bestcombination pattern, is operable to open the weighing hopper gates 2f(FIG. 6) specified by the best combination pattern, so that thecorresponding weighing hoppers discharge their articles into thecollecting chute 4, and to open the corresponding pool hopper gates sothat the emptied weighing hoppers may be replenished with articles.

The operation of the combination control unit 6 will now be described inbrief. At the beginning, each of the weighing hoppers 2-1, 2-2, . . .2-n contain a supply of the articles. The weight sensors 3-1, 3-2, . . .3-n measure the weights of the articles and produce the weight values W1through Wn which are sent to the combination control unit 6 for storagein the registers 6a-1, 6a-2 . . . 6a-n, respectively. The n-bit (n=10)counter 6b counts the timing pulses TP having the predeterminedfrequency to produce 2_(n) -1 combination patterns. Thus, when the firsttiming pulse TP arrives and is counted, the content of counter 6bbecomes 0000000001. As a result, the multiplexer 6c sends the firstweight value signal W1, from the first weight sensor 3-1 and stored inthe register 6a-1, to the arithmetic circuit 6g, which responds byperforming the operations specified by equations (1) and (2) above,thereby producing the signals indicative of the gross weight ΣW_(i) ofthe combination and of the deviation A (=|W₁ -W_(a) |) between ΣW_(i)and the set target value W_(a). Since the gates 6m, 6n are open for theinitial combinatorial computation, the deviation value A is transferredto and stored in the minimum deviation register 6j, and the content (thecombination pattern 0000000001) of n-bit counter 6b is stored in thebest combination memory 6k. Comparator 6h compares the gross weightΣW_(i) (= X) against the maximum value M_(a) and the minimum valueM_(i), and increments the counter 6i when the relation M_(i) ≦X≦M_(a)holds. Thenceforth, when the second timing pulse TP is generated, thepulse is counted by counter 6b, whose content (combination pattern) isincremented to 0000000010. Consequently, the weight value output W2 ofthe weight sensor 3-2 provided on the second weighing hopper, whichweight value is stored in the register 6a-2, is delivered to thearithmetic unit 6g which then performs the operations of equations (1)and (2) to produce the signals indicative of the gross weight ΣW_(i)(=X) and of the deviation value A (=|W₂ -W_(a) |). The comparator 6hthen determines whether equation (3) is satisfied; if it is, then thecontent of counter 6i is incremented by one. The comparator 6p,meanwhile, compares the deviation value A with the content B (=|W₁-W_(a) |) of the minimum deviation register 6 j. If the relation A≧Bholds, then neither the register 6j nor the best combination memory 6kis updated; if A<B holds, the deviation value A is transferred to andstored in register 6j, and the content of counter 6b is transferred toand stored in memory 6k. The operation described above is repeated untilall 2^(n) -1 combinations have been generated. At such time the contentof the minimum deviation register 6j will be the minimum deviation valueobtained from the 2^(n) -1 combinations, and the content of the bestcombination memory 6k will be the combination pattern that gave saidminimum value. The best combination is thus selected from the total of2^(n) -1 possible combination patterns. Thenceforth, when the value ofthe count in counter 6i is one or more, the output of the counter 6i,namely a discharge start signal DCS (now logical "1"), and thecombination pattern stored in the best combination memory 6k, areapplied to the discharge control unit 7. When the value of the count incounter 6i is one or more, the discharge control unit 7 successivelyopens the hopper gates 2f of those weighing hoppers corresponding to the"1" bits of the input combination pattern, the designated hopper gatesopening in turn with the prescribed intervening time delay, whereby thearticles in the corresponding weighing hoppers are discharged into thecollecting chute 4, after which the discharge control unit 6 opens thecorresponding pool hopper gates to replenish the emptied weighinghoppers with articles. Further, the dispersing feeders corresponding tothe now-empty pool hoppers are vibrated for a fixed length of time toresupply these pool hoppers with articles. This completes onecombinatorial weighing cycle, which may be repeated as often asrequired, to provide batches of the articles, each batch having a totalweight equal or closest to the set target weight. It should be notedthat when the content of counter 6i is zero in the foregoing operation,articles are not discharged and each of the weighing machines must besupplemented with articles to resume the combinatorial computations.

Referring now to FIG. 8, the discharge control unit 7 includes a memory7a for storing the best combination pattern, assumed here to be1000101011, received from the combination control unit 6. A flip-flop(FF) 7b, which receives the discharge start signal DCS from thecombination control unit 6, is set by the signal DCS and reset by adischarge end signal DCE, namely a signal that goes to logical "1" uponthe completion of a discharge operation. A flip-flop 7c, which isinitially in the reset state, is set a predetermined period of timeafter the start of a discharge operation, and is reset after thedelivery of a discharge command signal DCC to a weighing hopper, thesetting and resetting operation being repeated in the manner described.When FF 7b is set by the discharge start signal DCS obtained from thecombination control unit 6, an AND gate 7d is opened to provide acounter 7f with clock pulse CP of a constant frequency generated by anoscillator 7e. The clock pulses CP are counted by a counter 7f whoseoutput N, indicative of the status of the count, is applied to acomparator 7g. The latter compares the value N with a set value Ns andproduces a "time over" signal TOS when N becomes equal to Ns. The signalTOS clears the counter 7f, sets FF 7c and is applied to a counter 7h,whose status Nc is incremented to a value of one as a result. When thecounted value Nc (=1) enters a controller 7i, the latter sends adischarge command signal DCC to the weighing hopper 2-1, which is thathaving the lowest number among the weighing hoppers 2-1, 2-2, 2-4, 2-6,2-10 corresponding to the "1" bits in the best combination pattern1000101011, whereby said weighing hopper is made to discharge itsarticles. The discharge command signal DCC is also fed through an ORgate 7j to reset FF 7c. A counter 7k is provided to store the number of"1" bits in the best combnation pattern, namely the number Nh ofselected weighing hoppers (where Nh=5 in the present example). Acomparator 7m constantly compares the status of the count Nc in counter7h with the status of the count Nh in counter 7k to detect whether Ncand Nh are equal.

When Ff 7c is reset by the discharge command signal DCC, AND gate 7dopens and counter 7f again starts counting the clock pulses CP. When thevalue of the count N becomes equal to the set value Ns, which will occurafter a predetermined period of time, the comparator 7g issues thesignal TOS to clear the content of counter 7f to zero, set FF 7 andincrement counter 7h (i.e., Nc) to a value of two, just as describedabove. The controller 7i now responds by sending a discharge commandsignal DCC to weighing hopper 2-2, which is that having the secondlowest number, and to FF 7 to reset the same. Thenceforth, and insimilar fashion, the signal TOS is produced whenever a predeterminedperiod of time has elapsed from the issuance of the discharge end signalDCC, with the content of counter 7h being incremented by one step tothree, four and then five each time the signal TOS arrives. Accordingly,the weighing hoppers 2-4, 2-6, 2-10 are provided with the dischargecommand signal, in the mentioned order, as the signal TOS is produced.When a total of five of the signals TOS have been generated, this isreflected by the value of the count Nc in counter 7h, establishing thecondition Nc=Nh=5. When this occurs, the comparator 7m responds byissuing the discharge end signal DCE, whereby FF7b is reset and AND gate7d closed, ending the discharge operation.

Reference will now be had to FIG. 9 to describe another embodiment of acombinatorial weighing apparatus according to the present invention. Theapparatus includes inner and outer chutes 4c, 4d defining independentdischarge paths, and weighing hoppers 2-1, 2-2, . . . 2-n, each havingtwo weighing hopper gates 2f₁, 2f₂, disposed in a circular array abovechutes 4c, 4d inwardly of the rim of the outer chute 4d. The weightsensors 3-1, 3-2, . . . 3-n weigh the articles introduced into therespective weighing hoppers 2-1, 2-2, . . . 2-n, and deliver signalsindicative of these weights to the combination computing unit 6. Thelatter responds by computing combinations based on the weight values,and by selecting two "best" combinations giving first and second totalweight values equal to a preset target weight or closest to the targetweight. The combination computing unit 6 then provides the dischargecontrol unit 7 with a discharge command signal for each of the weighinghoppers selected in accordance with the combinatorial computations. Thedischarge control unit 7 sends the acquired discharge command signalsfor the first set of selected weighing hoppers, after successivepredetermined time delays, to said weighing hoppers in either increasingor decreasing numerical order. These weighing hoppers, upon receipt ofthe discharge command signals, successively release their articles intothe inner chute 4c as their inner weighing hopper gates 2f₁ are openedin the abovementioned order in response to the discharge signals.Concurrently, or immediately after the above operations, the dischargecontrol unit 7 sends the acquired discharge command signals for thesecond set of selected weighing hoppers, after successive predeterminedtime delays, to said weighing hoppers in either increasing or decreasingnumerical order. These weighing hoppers, upon receipt of the dischargecommand signals, successively release their articles into the outerchute 4c as their outer weighing hopper gates 2f₂ are opened in theabovementioned order in response to the discharge signals.

When the articles are discharged into the inner and outer chutes 4c, 4din this manner, the discharge from the weighing hoppers 2-1, 2-2, . . .2-n is effected one at a time with a time delay intervening between eachdischarge, so that large quantities of the articles do not accumulatewithin the chutes, particularly within the outer chute 4d where its flowpath is narrowed. The articles can therefore be delivered from thechutes assuredly without forming bridges that would cause the articlesto pile up.

In each of the foregoing embodiments the weighing hoppers are providedin a circular array. It should be obvious, however, that the inventioncan also be applied in a case where the weighing hoppers are arrayed inparallel rows, with opposing weighing hoppers being so controlled as todischarge their articles non-simultaneously.

It should also be obvious that the invention can be applied to aso-called combination computing-type automatic counting apparatus thatoperates by computing combinations based on a plurality of numericalvalues obtained by dividing weight values, obtained from a plurality ofweighing machines, by the weight of each article fed into the weighingmachines, these numerical values therefore indicating the numbers of thearticles fed into the machines, selecting the best combination ofnumerical values that gives a total number equal or closest to a setnumber, and causing the weighing hoppers corresponding to the bestcombination to discharge there articles into an awaiting chute.

In accordance with the present invention as described and illustratedhereinabove, combinations are computed based on the weights of articlescharged into each of a plurality of weighing hoppers disposed above achute or chutes, a combination of these weights that gives a totalweight value equal or closest to a set weight value is selected, andarticles are discharged from those weighing hoppers corresponding to theselected combination. According to a feature of the invention, theselected weighing hoppers are caused to discharge one at a time insuccessive fashion with a time delay intervening between each discharge,thereby preventing a concentrated accumulation of the articles in thechute, as would otherwise occur if all of the selected weighing hopperswere to discharge simultaneously. This in turn prevents the articlesfrom forming bridges and, hence, from clogging the chute, so that thearticles can be recovered from the chute reliably regardless of the typeof article and the shape of the chute.

Although a certain preferred embodiment has been shown and described indetail, it should be understood that many changes and modifications maybe made therein without departing from the scope of the appended claims.

What we claim is:
 1. A combinatorial weighing system comprising:meansfor supplying articles in a plurality of paths to provide acorresponding plurality of measured, individual batches of articles inthe respective said plurality of paths, said supplying means includingmeans for measuring the weight of each of said plurality of individualbatches and producing a numerical value signal representative of themeasured weight thereof and for retaining said plurality of measuredarticle batches in the respective said paths; means for storing thenumerical value signals of said measured batches retained in each saidpath and identifying each said retained batch with the corresponding,stored numerical value signal; means for selecting from said storednumerical value signals a specific combination of plural storednumerical values which provide a sum numerical value satisfying apredetermined condition; means for selectively discharging the plural,retained article batches respectively identified by said selected,specific combination of plural stored numerical values in time-sequencedintervals from the respective retaining means; and means for collectingsaid selectively and sequentially discharged, plural article batches. 2.A system as recited in claim 1 wherein:said selecting means selectsfirst and second specific combinations of respective, first and secondpluralities of said stored numerical values, each providing a sum valuesatisfying said predetermined condition; means associated with each saidpath for directing a batch retained therein, upon discharge, into aselected one of first and second separate discharge paths in accordancewith the selection of the stored numerical value identifying that batchin one of said first and second specific combinations, respectively;said collecting means includes first and second collecting meansassociated in common with the respective said first and second dischargepaths for separately collecting articles respectively discharged throughsaid first and second separate discharge paths; and said selectivedischarging means selectively discharges said first and secondpluralities of retained article batches identified by the respectivefirst and second specific combinations in time-sequenced intervalsthrough said respective first and second separate discharge paths.
 3. Asystem as recited in claim 2, wherein said selective discharge meansdischarges said first and second pluralities of retained article batchesof the respective said first and second specific combinations insuccession.
 4. A system as recited in claim 2, wherein said selectivedischarge means discharges said first and second pluralities of retainedarticle batches of the respective said first and second specificcombinations concurrently.